Product and process for filtering tobacco smoke



July 25, 1967 A. GARZIA 3,33

PRODUCT AND PROCESS FOR FILTERING TOBACCO SMOKE Filed Dec. I0, 1964 INVENTOR.

ALDQ GARZIA ATTORNEYS.

United States Patent 3,332,427 IRGDUCT AND PROCESS FOR FILTERING TOBACtIO SMOKE Aldo Garzia, Lotli, Italy, assignor to Istituto Chemioterapico Italiano S.p.A., Milan, Italy, a corporation Filed Dec. 10, 1964, Ser. No. 417,452 23 Claims. (Cl. 131-103) This invention relates to the treatment of tobacco smoke to reduce or eliminate the presence of undesirable constituents in the smoke and is particularly concerned with treating tobacco smoke with a purifying agent including a formazan and/ or a sorbitol-furfural.

In smoking tobacco, products of combustion are formed or released. Although some of the constituents c.g. light hydrocarbons, in the mainstream of tobacco smoke (i.e. in the smoke stream destined to reach the mouth of the smoker), are desirable from the standpoint of taste, flavor and aroma, other constituents, e.g. heavy hydrocarbons, are undesirable in that they may harmfully affect the health of the smoker, are irritating to the smoker, or are a nuisance in that they may stain the smokers teeth and hands. Among the undesirable constituents of tobacco smoke are the tar-like materials, eg phenolic tars, and the polycyclic aromatic hydrocarbons, for instance, anthracene, benz(a)anthracene, benzo(a)pyrene, fluorene, pyrene, dibenzo(a, i)pyrene, dibenzo(a,h)anthracene, benzo(c)phenanthrene and the like, particularly the higher aromatic polycyclics containing from 4 to 6 condensed IIIITS.

Iii accordance with the present invention, the amount of the undesirable constituents in tobacco smoke is reduced while maintaining enough flavor in the smoke by contacting the tobacco smoke with a nontoxic tobacco smoke purifying agent including formazans, sorbitol-furfurals or their combination. The formazans have the formula wherein R can be hydrogen, aryl, e.g. containing 6 to 11 carbon atoms, such as phenyl, alkyl, e.g. lower alkyl, such as ethyl, and each R can be the same or different. Specific examples of the formazan include one where R is hydrogen in all instances, one Where R is phenyl in all instances (triphenyl formazan) and one where R is ethyl in all instances (triethyl formazan). The flavorless and tasteless formazans, e.g. triphenyl formazans, are particularly suitable. The formazans are particularly effective in reducing the polycyclic hydrocarbon content of tobacco smoke. It is believed that the formazans when contacted with the tobacco smoke, quickly react with polycyclic hydrocarbons in the smoke to form a relatively waterinsoluble compound or complex which is retained in a support, e.g. filter unit.

The sorbitol-furfural is produced by the condensation of sorbitol and furfural according to known methods, for example, by subjecting the furfural and sorbitol to a condensation reaction in the presence of acid catalysts While removing or tying up the Water split off during the condensation reaction. The condensation products include those prepared by condensing from about 1 to 3 mols of furfural for each mol of sorbitol. The preferred condensa tion product is one prepared by condensing furfural and sorbitol on a mol per mol basis, for instance, to produce the 2,4-acetal of sorbitol, e.g. 2,4-monofurfurylidenesorbitol having the chemical structure which is a nontoxic, flavorless product. The sorbitol-furfurals are particularly effective in reducing the phenolic tar content of tobacco smoke. It is believed that the sorbitol-furfural, when contacted with the tobacco smoke, quickly reacts with phenolic tar in the smoke to form a relatively water-insoluble compound or complex which is retained in a support, e. g. filter unit.

The present invention can be advantageously employed in connection with a support which can be used to condition tobacco smoke emanating from a lighted cigarette, pipe or cigar for inhalation by the smoker. The support can serve as a filtering material as Well as a carrier for the smoke purifying agent in the form of a unitary, elongated, rod-like mass adapted to afford passage of tobacco smoke through it. The purifying agent can be in corporated into the filtering material in amounts sufiicient to reduce the content of undesirable constituents in the smoke but insuflicient to significantly retard the passage of smoke. These amounts will depend upon the content of undesirable constituents in the smoke and will generally range from about 1 to 500 micrograms or more of formazans and/or sorbitol-furfurals for a standard cigarette filter tip, usually from about 5 to 100 micrograms when using a combination of formazans and soribtolfurfurals, and usually from about 5 to micrograms when using either a formazan or a sorbitol-furfural alone. Moreover, when using a combination of formazans and sorbitol-furfurals, the combination can comprise from about 10 to weight percent, preferably from about 40 to 60 weight percent, of formazan based on the weight of the formazan and sorbitol-furfural. The formazans and sorbitol-furfurals can advantageously be used separately in the same filter unit wherein a formazan is incorporated in one of a pair of filter portions arranged in tandem in the filter unit and a sorbitol-furfural is incorporated in the other portion, preferably the portion nearest the tobacco.

The support for the purifying agent can constitute a filter unit which is utilizable as a mouthpiece or holder for a cigarette or cigar, or an integral part of the cigarette or cigar, or it may be made applicable for use as a filter for a pipe. The support can be in the form of a mass of any one of a number of materials which provide a large surface area for impingement of the smoke particles and which provide surfaces permitting adherence of the purifying agent deposited. The support can be a conventional filter unit employed with cigarettes, cigars or pipes and these units include a resinous filter, e.g. foamed plastic, a roll of crirnped paper, or a fibrous filter. They include foamed polyurethane filter units, filter units prepared from a crimped continuous filament tow of cellulose acetate fibers, filters of a textile character which include those prepared from fibers of viscose, cotton, nylon, polyamides and polyesters; filter units of asbestos, or cork, of natural and synthetic sponges, and even of granular material. When fibers are used, in addition to being in tow, i.e. parallel, they can be in other conventional forms such as wads, or fibrous masses interleaved with paper and rolled into a convoluted configuration. Cellulose acetate and other synthetic thermoplastic fibers can be used Where the fibers are in substantially longitudinal parallelism and are coextensive with the body of the filter. The filter can be a continuous strand, e.g. tow, of 1000 to 35,000 filaments, the filaments being of 17 to 3 denier and having 4 to crimps per inch.

A convenient way to construct an absorbent paper body of a cigarette filter tip so that it is honeycombed with tortuous air passages the walls of which are coated with the purifying agent, is to roll spirally or accordion pleat previously coated crepe paper so that the corrugations of the crepe paper run parallel with the axis of the roll or accordion pleats. It is desired that the filter material be packed by rolling, accordion pleating or any other convenient method that will keep the air channels formed by the corrugations open. corrugations in the crepe paper are particularly suitable to form tortuous conduits by virtue of their irregular configuration. Helped by the turbulence of the eddy currents forming in the tortuous conduits, greater intimacy of contact of the smoke with the coated walls of the conduits is attained and thereby a higher measure of adsorption.

The purifying agent can be incorporated into the filtering material using conventional methods. For instance, the material can be impregnated with a suspension or a solution of the agent followed by removal of excess sol vent, or the agent can be added to the surface of a pervious supporting mass such as fibrous filter material prior to its fabrication into a filter cartridge, e.g. a tip for a cigarette. For instance, a filter roll or the like of suitable paper, foam plastic, fibrous material or the like can be immersed once or several times in a solution of the agent and excess solution absorbed by the filter can be removed, e.g. by centrifuging; absorbing paper sheets which subsequently are to be rolled into filters may be sprayed with a solution of the agent or the agent added as a dry powder or as a powder kept damp by use of a humectant and thereafter the moistened sheet is dried. One convenient method for impregnating a filter cartridge involves the use of a syringe, for instance, a medical type syringe. In this method, a solution containing, for instance, from about 1 to 500 micrograms of the agent in from about 1 to 5 cc. of a volatile solvent is injected into the filter tip with the syringe, the solution disperses substantially uniformly in the area of the filter tip and the solvent is allowed to evaporate to provide a filter tip containing the agent. Any volatile solvent which is chemically inert to the filter and agent can be used. Suitable solvents include the aliphatic alcohols e.g. lower alkanols, such as methanol, ethanol and isopropanol.

The present invention can be exemplified with a cigarette having a porous smoke filter associated with one end, wherein at least a portion of the filter contains purifying agent as well as a porous filter element adapted for the passage of tobacco smoke therethrough and impregnated with purifying agent. Such filters are illustrated in the drawing, wherein:

FIGURE 1 is a longitudinal section through a filter type cigarette, according to the present invention; and,

FIGURE 2 i a longitudinal section through a cigarette and a cigarette holder wherein the filter element is disposed in the cigarette holder.

Referring now to the drawing, and particularly to FIG- URE 1, a typical cigarette is shown comprising a cylindrical body of tobacco 1, Wrapped in cigarette paper 2 and having secured to one end thereof filter element 3, comprising a cylindrical reinforcing paper 4 and a porous absorbent filter body 5, impregnated with the purifying agent.

In FIGURE 2, reference numeral 11 indicates a cigarette without a filter which is removably inserted into a filter tip 12. In the intermediate portion of filter tip 12, between the mouthpiece 13 and the cigarette holding portion 14, a porous absorbent filter element 15 is inserted which again contains smoke purifying agent.

Filter elements 3 and 15 have been illustrated as an impregnated porous body by way of example only. The filter element, of course, may be of any other type, such as fibrous material, foamed or porous plastic, absorbent paper or any other structure which may be impregnated with, or hold the purifying agent and through which tobacco smoke may pass. A particularly advantageous paper filter unit for removing polycyclic hydrocarbon from tobacco smoke can be prepared by first treating the paper with an alcoholic solution of sorbitol-furfural, drying the paper, treating the paper with an alcoholic solution of a formazan, drying the paper, and fabricating the paper into a filter unit. A particularly advantageous foamed plastic filter is one containing a formazan.

It is also within the scope of the present invention to incorporate the purifying agent into the raw material from which the filter element is produced. Thus it is possible to add a solution to the paper pulp from which the filter-forming paper will be produced. In the case of foam plastic filters, the purifying agent may be incorporated into the mass prior to its foaming, or purifying agent may 'be deposited on the foamed plastic by impregnating it with a solution of the purifying agent and subsequently drying it.

The following examples are given as illustration only and are not to be considered limiting.

Example I A syringe is used to inject a 1 cc. ethanol solution containing 50 micrograms of triphenyl formazan into a cellulosic filter element, 15 mm. in length and composed of compressed cellulose acetate filaments containing 12,000 filaments of 5 denier per filament and having 7 crimps per inch. The impregnated filter is placed on a screen, and warm air is passed from below through the screen and to the filter to dry the filter. The dried filter, containing 50 micrograms of triphenyl formazan is attached to a cigarette having tobacco producing smoke, the cigarette is lit, tobacco smoke is drawn through the filter and substantial amounts of polycyclic aromatic hydrocarbons containing from 4 to 6 condensed rings are removed from the smoke.

Example ll Fifty micrograms of the acetal condensation product of 1 mol of sorbitol and 1 mol of furfural in 1 cc. of ethanol is sprayed on a sheet of crimped, absorbent paper which subsequently is to be rolled into a cigarette filter. The paper is dried, is sprayed with 1 cc. of ethanol containing 50 micrograms of triphenyl formazan, is again dried, and is rolled into a filter for a cigarette. The filter is attached to a cigarette, the cigarette is lit, tobacco smoke is drawn through the filter, and substantial amounts of phenolic tars are removed from the smoke.

Example 111 A syringe is used to inject a 1 cc. ethanol solution conatining 50 micrograms of triphenyl formazan into a foamed porous polyurethane cigarette filter which is dried, attached to a cigarette, the cigarette is lit, tobacco smoke is drawn through the filter and substantial amounts of polycyclic hydrocarbons are removed from the smoke.

Examples 1V and V Essentially the same procedure used in Example III is followed except the following compounds are substituted for the triphenyl formazan:

Example Compound IV NH=N 0 ]1 NH2N V ethyl-N=N C ethyl ethyl-NHN Example VI Essentially the same procedure used in Example III is followed except that the compound 1 cc. ethanol solution containing 50 micrograms of an acetal of sorbitol having the formula into another portion of a foamed polyurethane cigarette filter tip. The portions are dried and arranged in tandem to form a filter tip. The portion of the filter tip containing the acetal of sorbitol is attached to a cigarette to provide a cigarette comprising a tobacco-filled portion and a filter-tip connecting to and serving as smoke conditioner for the tobacco-filled portion when the cigarette is lit and drawn upon. The cigarette is lit, tobacco smoke is drawn through the filter, and substantial amounts of phenolic tars and polycyclic hydrocarbons are removed from the smoke.

In view of the foregoing, the gist of the present in vention will be obvious to those versed in the art who can be applying current knowledge readily adapt it for various applications without omitting features that fairly constitute essential characteristics of the generic or specific aspects of this invention, and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

It is claimed:

1. A method for treating tobacco smoke to reduce the proportion of undesirable components therein which comprises contacting tobacco smoke with a purifying agent including a mixture of a formazan having the formula wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms, and lower alkyl; and an acetal or sorbitol prepared by the condensation of from about 1 to 3 moles of furfural for each mol of sorbitol.

2. A method for treating tobacco smoke to reduce the proportion of undesirable components therein which comprises contacting tobacco smoke With a purifying agent having the formula wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms and lower alkyl.

3. The method of claim 2 wherein the purifying agent is triphenyl formazan.

4. A method for treating tobacco smoke to reduce the proportion of undesirable components therein which comprises contacting tobacco smoke with a purifying agent which is an acetal of sorbitol prepared by the condensation of from about 1 to 3 mols of *furfural for each mol of sorbitol.

5. The method of claim 4 wherein the purifying agent is the acetal of sorbitol prepared by the condensation of about 1 moi of furfural and 1 mol of sorbitol.

6. A cigarette having a porous smoke filter associated with one end thereof, at least a portion of the filter containing a purifying agent including a mixture of a formazan having the formula RN=N /C-R RNHN/ wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms, and lower alkyl; and an acetal of sorbitol prepared by the condensation of from about 1 to 3 mols of furfural for each mol of sorbitol.

7. A cigarette having a porous smoke filter associated with one end thereof, at least a portion of the filter containing a purifying agent having the formula RN=N /CR RNHN/ wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms and lower alkyl.

8. The cigarette of claim 7 wherein the purifying agent is triphenyl formazan.

9. A cigarette having a porous smoke filter associated with one end thereof, at least a portion of the filter containing a purifying agent which is an acetal of sorbitol prepared by the condensation of from about 1 to 3 mols of furfural for each mol of sorbitol.

10. The cigarette of claim 9 wherein the purifying agent is the acetal of sorbitol prepared by the condensation of about 1 mol of furfural and 1 mol of sorbitol.

11. As an article of manufacture, a porous absorbent filter element adapted for the passage of tobacco smoke therethrough and for the treatment of the tobacco smoke during said passage, said filter element containing a purifying agent in an amount effective to treat the tobacco smoke and including a mixture of a formazan having the formula RN=N /CR RNHN/ wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms, and lower alkyl; and an acetal of sorbitol prepared by the condensation of from about 1 to 3 mols of furfural for each mol of sorbitol.

12. As an article of manufacture, a porous absorbent filter element adapted for the passage of tobacco smoke therethrough and for the treatment of the tobacco smoke during said passage, said filter element containing a purifying agent in an amount effective to treat the tobacco smoke and having the formula wherein R is selected from the group consisting of hydrogen, aryl containing from about 6 to 11 carbon atoms and lower alkyl.

13. The filter element of claim 12 wherein the purifying agent is triphenyl formazan.

14. As an article of manufacture, a porous absorbent filter element adapted for the passage of tobacco smoke therethrough and for the treatment of the tobacco smoke during said passage, said filter element containing a purifying agent in an amount effective to treat the tobacco smoke and which is an acetal of sorbitol prepared by the condensation of from about 1 to 3 m-ols of furfural for each mol of sorbitol.

15. The filter element of claim 14 wherein the purifying agent is the acetal of sorbitol prepared by the condensation of about 1 mol of furfural and 1 mol of sorbitol.

16. The filter element of claim 15 wherein the purifying agent has the formula 17. The filter element of claim 11 wherein the purifying agent is a mixture of triphenyl formazan and the S acetal of sorbitol prepared by the condensation of abom 1 mol of furfural and 1 mol of sorbitol.

18. The filter element of claim 11 wherein the element includes a porous resinous composition.

19. The filter element of claim 12 wherein the element includes a porous resinous composition.

20. The filter element of claim 19 wherein the purifying agent is triphenyl formazan.

21. The filter element of claim 11 wherein the element is composed of porous absorbent paper which was first impregnated with the acetal of sorbitol and was then impregnated with the formazan.

22. The filter element of claim 21 wherein the acetal of sorbitol was prepared by the condensation of 1 mol of furfural and 1 mol of sorbitol.

23. The filter element of claim 22 wherein the formazan is triphenyl formazan.

No references cited.

SAMUEL KOREN, Primary Examiner.

D. DONOHUE, Assistant Examiner. 

1. A METHOD FOR TREATING TOBACCO SMOKE TO REDUCE THE PROPORTION OF UNDERSIRABLE COMPONENTS THEREIN WHICH COMPRISES CONTACTING TOBACCO SMOKE WITH A PURIFYING AGENT INCLUDING A MIXTURE OF A FORMAZAN HAVING THE FORMULA 